One possible explanation for these findings is that when presented with complicated problems, the mind can often get stuck, finding itself tracing back through certain pathways of thinking again and again. (inc.com)
Evolution may follow certain pathways just because certain interactions may be negative, other interactions may be positive. (sciencedaily.com)
They can be made to promote certain pathways, encourage specific behaviors, even elicit emotional reactions. (multibriefs.com)